Cross-site investigation on head-related and headphone transfer functions: variabilities in relation to loudness balancing

Acta Acustica, vol. 5, pp. 58

Abstract

Headphone transfer function (HpTF) and head-related transfer function (HRTF) measurements are crucial in acoustic science and in binaural virtual acoustic applications. Yet, their measurement set-up, procedure or post-processing is different for nearly every lab, especially for the HRTF measurements. To compare findings between different labs, these measurement deviations have to be quantified alongside with their influence on perceptual aspects. In the scope of a cross-site investigation on loudness balancing between headphone and loudspeaker listening, a set of HpTFs with three different headphones (open, closed, insert earphones) and HRTF close to the eardrum were measured in 14 participants travelling to two different measurement sites at Aachen and Oldenburg. Though set-ups for measuring the HRTF are very different between sites, the gathered HRTFs are quite consistent across them. For the measured HpTFs, across sites the open headphones consistently yield a slightly lower variability in the range from 70 to 5000 Hz than the closed one while the insert earphones exhibit much higher variabilities and a limited range of reproducible results. The difference in loudness balancing across labs could well be predicted by site-specific systematic differences in HpTFs with the exception of 1 kHz narrowband stimulus. This clearly indicates the limits in comparability of HpTFs and loudness balancing across labs and the importance of using headphones with high repeatability like the open ones used in this investigation.

Authors 5

1. Michael Kohnen corresponding Aachen Institute for Hearing Technology and Acoustics

   RWTH Aachen University

   Affiliation as printed

   Institute for Hearing Technology and Acoustics, RWTH Aachen University, 52056 Aachen, Germany

2. Florian Denk

   Carl von Ossietzky Universität Oldenburg · Hearing4all

   Affiliation as printed

   Medizinische Physik & Cluster of Excellence Hearing4All, Universität Oldenburg, 26111 Oldenburg, Germany

   Now at: German Institute of Hearing Aids, Anschützsraϐe 1, 23562 Lübeck, Germany

3. Josep Llorca-Bofí Aachen Institute for Hearing Technology and Acoustics

   RWTH Aachen University

   Affiliation as printed

   Institute for Hearing Technology and Acoustics, RWTH Aachen University, 52056 Aachen, Germany

4. Birger Kollmeier

   Carl von Ossietzky Universität Oldenburg · Hearing4all

   Affiliation as printed

   Medizinische Physik & Cluster of Excellence Hearing4All, Universität Oldenburg, 26111 Oldenburg, Germany

5. Michael Vorländer Aachen Institute for Hearing Technology and Acoustics

   RWTH Aachen University

   Affiliation as printed

   Institute for Hearing Technology and Acoustics, RWTH Aachen University, 52056 Aachen, Germany